The present invention relates to a keyboard having keys and to a key for inputting characters, wherein the key is arranged to produce a character in response to the press of the key once. Also the invention relates to a telephone apparatus comprising such a keyboard.
The use of mobile phones and other portable devices is also becoming common in the handling and transfer of alphanumeric information. This requires having a small-sized manmachine interface (MMI), which is capable of easily handling more than 30 letters, numbers from 0 to 9, and about ten special characters (+, #, *, etc.), i.e., a total of, for example, 50 characters or more. The entity of the produced characters is called a set of characters. The operational requirement is the same as, e.g., that of a computer keyboard, but the size should be considerably smaller, and the device should also be suitable for mobile use in other ways. An additional requirement made of the device is, e.g., good manufacturability and low costs, as well as suitability for different kinds of user environments and for the implementation of many different types of sets of characters. The device, presented here, which meets these requirements, is called a keyboard while an alphanumeric keyboard is called an A/N keyboard.
One way of reducing the size of an A/N keyboard is to reduce the size of an individual key to the extent that the keys are handled by means of a special manipulator instead of using fingers such as a stick, as indicated by the development path of the miniaturisation of an A/N keyboard, shown in FIG. 1. Another way is to make one key serial-operationally multi-functioning, i.e., sequential, so that, within a specific time window, one press denotes a number, two presses a first letter, three presses a second letter, etc. For example, an A/N keyboard used with motions, currently in use the Global System for Mobile Communications. GSM phones, functions in this way, as shown in FIG. 2. The keyboard functions merely as a numeric keyboard and, when separately selected, on an A/N keyboard, so that one press within a specific period of time (e.g., approx. one second) denotes a first letter alternative, two presses a second letter alternative, etc. In a widely known solution, the sensitivity of a key to the number of presses can be adjusted so that the key either identifies several presses or each press is followed by the main alternative, i.e., usually the selection of a number. The pressing of a key is identified by electronics, so that the pressed key connects a row conductor, at the point of the key, to a column conductor, located at the same point, and by identifying, by means of electronics, the conductors connected to each other.
The problem of both a traditional and a miniaturised keyboard is that they neither fit in a sufficiently small space nor is it possible to have clear numeric keys on a small A/N keyboard. From the viewpoint of a portable device, the problem is also the number of matrix conductors, required in keyboard coding, which, for e.g. 56 keys is 7+8 (7 rows, 8 columns), and the deformation of the row/column figure of the keyboard, when implementing for e.g., 56 keys physically for a 4*14 row matrix. The advantage of a sequential key function is a clear main function, e.g., numbers, but the disadvantage, from a user""s viewpoint,is the slowness of the letter functions and that it is difficult to understand.
A major technical development step should yet be taken from the above-described solutions, e.g., to graphic, interactive keyboards or to identifying writing by a hand movement. Hence, there is still need for a useful A/N keyboard, based on contact.
One solution for a key of a keypad is disclosed in publication DE 36 22 275, in which each key has two contact elements and the key is formed as a rocker button so that when the key is pressed in the middle both contact elements are contacted to activate a middle key function, when the key is pressed at left only the left contact element is contacted to activate a left key function, and when the key is pressed at right only the right contact element is contacted to activate a right key function. This solution allows three different key functions to occur by one press. At the time, however, more than three key functions are desired of one key, especially in mobile phones.
The present invention combines, from a user""s viewpoint, a single- and multi-functioning key so that there is only one key for a number of characters, however, so that each character is selected with a single press of the key. The present invention allows in the preferred embodiments 8-10 different key functions for each key by a single press of the key. As for its manufacture, the device is economical, because the number of conductors required for keyboard coding such as row and column conductors are smaller than in the well-known two-dimensional matrix conductor solutions. Therefore, e.g., 56 characters, which in matrix coding require 15 (7+8) conductors, can be decoded by means of 11 conductors which consist of the row and column conductors of a 4*4 matrix, as well as three conductors identifying the keyboard edge, thereby easily enabling the coding of more than 64 different kinds of characters.
The invention is characterized by that the key has a main contact which is always activated when the key is pressed, and at least one edge contact, which is activated, in addition to the main contact, when the key is pressed at the point or close to the point of the edge contact, and the activation of predetermined contacts correspond to the inputting of a predetermined character.